The present invention relates to temperature control. More specifically, the present invention relates to the regulation of electrical component temperature through the throttling of component communication based on information provided by a sensor and corrected by a component-specific calibration table.
Various methods exist in the art for controlling the temperature of electrical components in devices such as computers. An example of temperature regulation involves the utilization of one or more fans that operate continuously or periodically (under the direction of a controller based on control criteria) to move hot air away from the component(s). Problems with fan operation include a high level of noise as well as a substantial amount of energy consumption.
For computer temperature regulation, there is an effort currently by manufacturers to have the computer chipset (memory controller) xe2x80x98predictxe2x80x99 the thermal state of its associated memory device(s). This involves keeping a toll of recent accesses that may cause the device(s) to change temperature. When the chipset predicts that the memory device may exceed the prescribed temperature limits, it xe2x80x98throttlesxe2x80x99 (slows down the rate of) subsequent accesses. This throttling is performed over a long enough period to allow the device(s) to return to some desired temperature, and the cycle is then repeated.
FIG. 1 illustrates the layout of a typical memory system of a computer. Data is accessed from (read) or placed in (write) memory, such as Synchronous Dynamic Random Access Memory (SDRAM) 102 by a memory controller (chipset) 104 to be utilized by a processor, such as a central processing unit (CPU) 106. In throttling accesses to regulate temperature by methods in the art based on prediction, the chipset must make pessimistic assumptions about the thermal characteristics of the system. In particular, the chipset must assume that the installed devices heat rapidly and cool slowly (not knowing anything about the specific devices installed in that machine). For systems with poor thermal management capabilities, this is a correct and necessary assumption. For systems with better thermal management (better air flow, for instance) this results in lower than desired (lower than necessary) system performance.
This method can be described as an xe2x80x9copen loopxe2x80x9d control strategy because it bases its temperature regulation on prediction under xe2x80x98worst casexe2x80x99 scenario, not on real-time temperature feedback (xe2x80x98closed loopxe2x80x99 control).
FIG. 2 provides a flowchart describing an example process of predictive temperature regulation as used in the art. The memory device is read (or written to) 202 by the memory controller as is needed by the current operation. A count is being kept of the memory accesses with respect to time passage. As long as less than some prescribed threshold amount of memory accesses are performed in a unit of time 204, the memory will be continually accessed 202 without a throttling interruption (delay 206). If the number of accesses per unit of time exceeds the threshold amount, a delay 206 is incorporated after the subsequent access 208. During the delay 206, no memory accesses occur. Until a prescribed amount of cooling time has passed (established by xe2x80x98worst casexe2x80x99 scenario), there is an alternation 210 between memory accesses 208 and delay 206 to reduce the communication rate, thereby reducing device temperature. When the prescribed amount of cooling time has passed, the memory operation returns to the normal communication rate 212.
Another method in the art involves using a temperature sensor to read the xe2x80x98actualxe2x80x99 temperature of the memory and using this unadjusted temperature to determine a rate of memory operation. This method is provided in U.S. Pat. No. 6,021,076. Because no device-specific calibration is performed to compensate for differing thermal characteristics, the temperature sensor must be in direct thermal communication with the device, and it must be very accurate. Process technology may not readily produce a sensor with predictable and repeatable behavior, yielding a situation where the sensor temperature coefficient and linearity, for instance, vary from one device to another. Further, the electrical interface may not include provision for sensor signaling to the chipset. The addition of interface signals for this purpose would be very difficult and expensive. The standards bodies would need to revise the connector pinouts for commodity parts, impeding adoption.
FIG. 3 provides an illustration of a memory system utilizing non-corrected, xe2x80x98actualxe2x80x99 temperature measurement for temperature regulation as performed in the art. Because with this method there is no means for correcting imperfect temperature readings, the temperature sensor(s) 302 must be very accurate and are usually required to be in direct contact with the memory device(s) 304. As stated above, the kind of sensor accuracy necessary would be very expensive, and providing a sensor that is in direct thermal communication (e.g. direct contact) with the device would be very difficult and expensive.
It is therefore desirable to have a system for regulating temperature of electronic components that avoids the above-mentioned problems, improves performance for systems with better thermal management, and reduces manufacturing costs, in addition to having other advantages.